Electric gear-motor drive unit



March 21, 1961 G, LUBER ETAL 2,976,438

ELECTRIC GEAR-MOTOR DRIVE UNIT 4 Sheets-Sheet 1 Filed July 9, 1958 illlll $1 mw 1. 0 WM 5 k .M M r. F! Mw m #3 W F r. U FF March 21, 1961 F, G LUBER ETAL 2,976,438

ELECTRIC GEAR-MOTOR DRIVE UNIT Filed July 9, 1958 4 Sheets-Sheet 2 $1.1m Frpiprzdr if j 11111 1" F1155!!! 10111115011 Artfivz'M 6: 1712101} March 21, 1961 F. G. LUBER ETAL ELECTRIC GEAR-MOTOR DRIVE UNIT Filed July 9, 1958 4 Sheets-Sheet 3 MJM Fryiprzolr Z7. 2222222" 77225551! I 1 02222252227 March 21, 1961 LUBER H 2,976,438

ELECTRIC GEAR-MOTOR DRIVE UNIT Filed July 9, 1958 4 Sheets-Sheet 4 2,976,438 ELECTRIC GEAR-MOTOR DRIVE UNIT Frederick G. Luber, Milwaukee, Russell I. Robinson,

, Thiensville, and Arthur M. G. Moody, La Crosse, Wis., assignors to The Louis Allis Company, Milwaukee, Wis., a corporation of Wisconsin Filed July 9, 1958, Ser. No. 747,481

11 Claims. (Cl. 310-83) This invention relates to electric gear-motor drive units and refers more particularly to drive units capable of delivering a high stepped-up output speed. The drive unit of this invention is, therefore, especially well adapted to drive the impeller of a centrifugal compressor in a refrigeration machine. It should be understood, however, that the drive unit of this invention is by no means limited to this purpose, but, on the contrary, would prove advantageous for many applications where an exceptionally high speed drive is needed, as for instance centrifugal pumps and blowers.

Centrifugal compressors have not been employed heretofore in small refrigeration machines, principally for lack of a satisfactory drive means capable of driving the impellers at the speeds necessary to develop sufficient pressure with an impeller proportionately small enough to be used in the smaller sized units: In explanation, it should perhaps be pointed out that the pressure that can be developed by a rotating impeller is limited by its tip speed, i.e. the speed at which the periphery of the impeller travels. This speed can be increased in two ways, one of which is to increase the size of the impeller. This is possible only in the larger capacity machines. The other, of course, is to increase the revolutions per minute of the impeller. This is the only acceptable alternative in the smaller size refrigeration apparatus.

Since the conventional sixty cycle power source results in a maximum motor speed of 3600 r.p.m. for motors of the type which are used for this service, and since on smaller diameter impellers that speed is not nearly enough to develop the necessary pressure, it follows that a motor driven power unit for this purpose must step up United States p its speed. Suitable transmission gearing between the motor shaft and the output shaft is, of course, the simplest answer to this need, but to provide adequate lubrication for a drive unit which in some cases would have an output shaft speed well in excess of 25,000 r.p.m., presents difficulties not heretofore encountered.

Another problem which the invention had to take into account results from the fact that when the power unit is used to drive the impeller of a compressor in a refrigeration apparatus, its enclosure must complement the enclosure of the refrigeration apparatus and, in fact, form a part thereof to thus eliminate the objectionable consequences of running seals through which refrigerant can escape.

The present invention has successfully met both of these problems and has done so by providing a new combination electric motor and gear unit, characterized by the fact that both the motor and the gear unit are housed within a single, hermetically sealed enclosure into which the only opening is the clearance between the output shaft and the bore in the housing wall through which it passes, and by so arranging the structure that this wall is within the hermetically sealed chamber or housing of the refrigeration apparatus when the drive unit is used to power its impeller.

' 2,976,438 Patented Mar. 21, 1 9 61 With a view toward meeting the lubrication problem, the present invention has as another of its objects to improve the manner in which the bearings for the shafts are mounted and lubricant conducted thereto.

Still another purpose of this invention is to provide a drive unit of the character described which is far simpler in design and more rugged in construction than any heretofore available, and wherein all of the shaft bearings are carried by one unitary casting, so as to facilitate the obtention of the exact alignment and positional relationship needed in a high speed gear transmittion.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiments of the hereindisolosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate two complete examples of the physical embodiments of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

Figure l is a longitudinal sectional view through an electric gear-motor drive unit embodying this invention;

Figure 2 is a horizontal sectional view through Figure 1 on the plane of the line 2-2;

Figure 3 is a view on an enlarged scale similar to a portion of Fiigure l, to better illustrate the manner in which the shaft bearings are mounted and lubricated; and

Figure 4 is a view similar to Figure 3, but illustrating a modification of a portion of the lubricating system.

Referring now particularly to the accompanying drawings, the numeral 5 designates generally an electric motor having a stator 6 and a rotor 7 mounted on a shaft 8. The motor shaft 8 is disposed vertically and is drivingly connected to a vertical high speed output shaft 9 by means of a drive gear 10 fixed on the motor shaft and meshing with a driven pinion 11 fixed on the output shaft. Since the purpose of the unit is to provide a highspeed drive, the gear 10 is considerably larger in diameter than the pinion 11. For instance, the gear 10 may be seven times the diameter of the pinion so that with the motor shaft running at 3,600 r.p.m. the output shaft would travel at approximately 25,000 revolutions per minute.

The entire structure, i.e. the motor and the transmission gearing, is contained within one common hermetically sealed enclosure designated generally by the numeral 12 and comprising an upper section 13 which contains the motor, and a lower section 14 in which the gears are located, the two sections being in open communication with one another. The side wall 15 of the upper section is preferably cylindrical and has a water jacket 16 between it and the stator core 6, through which water or other cooling medium may be circulated, the cooling medium entering at the inlet 17 and leaving at the outlet 18, and having its flow directed by a helical baflie 16', connecting the inner and outer walls of the water jacket.

Since the unit is designed to operate with its shafts vertical, the closed end 19 of the motor housing forms the top thereof and preferably has an inspection window 21 therein to permit visual inspection of the motor interior, and particularly its direction of rotation. For convenience, this window is carried by a tubular plug 22 threaded into the top wall 19. The top wall 19 also may have the junction box 20 for the motor mounted thereon, into which the motor leads (not shown) extend to be connected to V the supply lines.

provides a gear case for the transmission gearing but also serves as a reservoir for liquid lubricant which is fed thereto through an oil filler port 23 in its side wall 24, the location of which determines the normal oillevel which should be slightly below the top of a boss 25 which rises from the bottom wall 26 of the lower section 14 and has a bore 25 through which the output shaft 9 passes for connection to a part to be driven.

The top wall 27 of the lower housing section has a round opening 28 therein to receive a flange 29 on the lower end of the upper motor housing section 13, with this flange seated upon a ledge 28' projecting from the edge of the opening. Cap screws 3% or the like secure the flange 2 9 to the ledge with a fluid-tight connection between the two enclosure sections, and allow for assembly of the unit.

Secured to the underside of the flange 29' by means of cap screws 31? is a bearing supporting structure or bracket, indicated generally by the numeral 31. This supporting structure or bracket is one integral unit, preferably a casting, and the hearings in which the motor and output shafts are journalled are carried by this one casting. This makes it possible to obtain the exact alignment and positional relationship of the the bearings needed for satisfactory operation of the unit.

The supporting structure or bracket 31 consists of a generally cup-shaped upper portion 32 having an imperforate side wall portion 32' and a bottom 34, and a horizontal wall 35 which forms the extreme bottom of the bearing supporting structure or bracket and is joined to the bottom of the cup-shaped upper portion by a vertically disposed arcuate wall 36. The imperforate side wall portion 32 of the supporting structure forms substantially a continuation of the adjacent portion of the motor housing side wall 15, to which it is tightly secured. The bottom 34 of the upper cup-shaped portion is not imperforate but, instead, is cut out as at 34 or otherwise sufiiciently open so as not to close off communication between the interior of the motor housing and the interior of the lower section 14 of the enclosure which contains the gears. At its center, the bottom 34 has a hollow boss 33 rising therefrom, and received in this boss is the upper motor shaft bearing 37. The lower motor shaft bearing 38 is mounted in the bottom wall 35-, and these two bearings constitute the sole support for the motor shaft.

The output shaft 9 is journalled in another pair of upper and lower bearings 39 and dil respectively, which, like the motor shaft bearings, are exactly coaxial. The lower bearing 49 is mounted in the bottom wall 35 alongside and correctly spaced from the bearing 38, and the upper output shaft bearing 39 is in the bottom 34 of the cup-shaped upper portion of the bearing supporting structure or bracket, so as to be at a level below that of the top motor shaft bearing 37. This offset relationship between the two upper bearings enables themotor shaft bearing 37 to be as large as needed to carry the heavy load imposed thereon Without weakening the support for either bearing and without lengthening the distance between the shafts and unduly increasing the size of the gears. It also has an important advantage with respect to lubrication, as will be hereinafter explained.

In order to assure coaxiality between the motor shaft bearings and the stator 6, which of course is necessary for the rotor 7 to run true within the stator, the upper end portion of the bearing supporting structure or bracket 31 is centered upon the flange 29 of the motor housing by being received in a counterbore 2? formed in the underside of the flange; and to assure maximum rigidity and stability for the structure, the bottom wall 35 of the bearing supporting structure or bracket is centered in and supported by a plurality of circumferentially spaced lugs 41 which project up from the bottomwall 26.

In view of the extreme high speed at which the output shaft 9 runs, it is of utmost importance that its bearings 4 39 and 40 and also the gear teeth be adequately lubricated at all times. Conventional lubricating expedients, as for instance having the gears run in a bath of oil, are out of the question because of the high speed of the gears. The problem is further complicated by the fact that when the drive unit is used to power the impeller of a refrigerating apparatus, the gaseous refrigerant is purposely caused to enter the common enclosure for the motor and gear transmission through the clearance between the shaft 9 and the bore 25'. This is done to prevent the passage of lubricant from the enclosure into the refrigeration system, which if permitted would seriously affect its functioning, to say nothing of the loss of lubricant from the gear case.

To effect the influx of gaseous refrigerant through the clearance between the drive shaft 9 and the bore 25' needed to prevent outward flow of lubricant, the interior of the enclosure is preferably communicated with a source of suction (or suitably negative pressure) through a duct 13' which opens to the enclosure at any point far enough above the oil level therein to preclude drawing off lubricant. Thus, for purposes of illustration, the duct 13 has been shown connected to the extreme upper portion of the motor housing 13, which location has the additional advantage of causing the gaseous refrigerant to flow through the motor where the centrifugal action of the rotating motor parts effects separation from the gaseous refrigerant of any lubricant which might be entrained therein. A unidirectional flow of gaseous refrigerant is thus maintained through the enclosure in a manner which effectively prevents the loss of lubricant.

Since separation of lubricant from the gaseous refrigerant flowing through the common enclosure for the motor and the gear transmission is the chief consideration determining the location of the vent or draw-off duct 13', it follows that if special means are provided to settle the oil out of the gaseous refrigerant, as for instance a strategically located settling zone in the enclosure, the outlet provided by the duct 13' can be placed almost anywhere in the enclosure walls as long as it is above the normal liquid oil level.

However, it should be recognized that while the flow of gaseous refrigerant through the motor and gear enclosure achieves the useful purpose of preventing the loss of lubricant into the refrigeration system, it aggravates the lubrication problem by frothing up the oil and particularly that oil which is in the form of a mist.

Accordingly, any oiling scheme which greatly agitates and excessively splashes the oil around must be avoided, but the oil must be continuously brought from the supply thereof in the bottom of the sump to all of the bearings and to the gear teeth during operation of the machine,

and must be fed thereto the instant the machine starts up.

The structure by which these prerequisites are satisfied constitutes an important part of this invention. It comprises generally a means to elevate oil from the supply thereof in the bottom of the gear housing to the topmost bearing, which is the upper motor shaft bearing 37, and suitable means for directing the oil which flows through this bearing, to all of the other bearings and to the gear teeth as well, together with means for catching and forming pools of oil at strategically located places upon shut down, for immediate delivery to the high speed bearings and the gear teeth upon starting of the unit.

Considering first the means by which oil leaving the top bearing reaches the other bearings and the gear teeth, it will be noted that the interior of the boss 33 which serves as a cage for the bearing 37 has a trough 45 around its side wall, in which some of the oil which runs down from the bearing 37 may accumulate. To assure against discharge of oil through the top of the bearing 37 and consequent loss thereof for use in the lower bearings and at the gear teeth, the upper end of the boss 33 has a bearing cap 46 secured therein which not only holds the bearing 37 in place, but also seals the space above this hearing.

The oil which accumulates in the trough 45 drains therefrom through a passage 47 which leads to the space 48 above the upper output shaft bearing 39. This space is closed at the top by a bearing cap 49, the underside of which has a stalactiform boss 50 pointing towards a conical well or pocket 51 in the upper end of the output shaft.

Hence, during operation, much of the oil which passes through the motor shaft bearing 37 is fed to the output shaft bearing 39 and from thereonto the gear teeth. Upon shut down, the oil on the underside of the bearing cap 49 runs down the sides of the boss 50 and drops into the well or pocket 51. A pool of oil is thus provided in direct juxtaposition to one of the critical points in the transmission system, namely the upper bearing 39 for the high speed output shaft. The oil in this pool is thrown into this hearing 39 by centrifugal force the instant the machine starts.

A somewhat similar way of promptly bringing oil to the gear teeth upon starting of the machine is also provided. For this purpose, the gear has its hub, Web and rim shaped to form an annular trough 52 in which oil from the bearing accumulates upon shut-down. The instant the machine is restarted, the oil in this trough is discharged through holes 53 drilled radially through the rim of the gear and leading from points slightly above the bottom of the trough to the teeth of the gear.

Due to the locations of the lower bearings 38 and 40,

no special means need be provided to supply them with lubricant. The oil which flows down from the bearings thereabove affords sufiicient lubrication.

The means for pumping or otherwise elevating the oil from the sump to the top motor shaft bearing in the preferred embodiment of the invention, comprises an axial bore 55 in the motor shaft extending from the bottom thereof, which is below the normal oil level, to a point adjacent to the bearing 37. At this point, a plurality-of radial holes 56 lead from the bore 55 to the outer surface of the shaft, and preferably these holes are drilled just beneath the bearing 37. Oil forced up through the bore 55 will thus discharge from the drilled holes 56 and splash against the side of the bearing cage or against a deflector 57 mounted in the cage just beneath the bearing 37. Consequently, much of the oil that issues from the holes 56 reaches the bearing 37, the rest flows down into the trough 45 for distribution to the other bearings and the scribed.

To pump the oil up through the bore 55 and out of the holes 56, the lower end of the bore is shaped to provide the effect of 'a centrifugal pump. This is accomplished by inserting a bored plug 58 in the end of the shaft, the bore of which has a small diameter inlet 59 and a taperingly increased outlet 60.

Another way of bringing oil from the sump to the upper bear-ing 37 is illustrated in Figure 4. In this case the lower end of the motor shaft has a helical elevator 61 fixed thereon which operates in' a cylinder 62 to pump oil through a duct 63 up to the bearing 37.

Whatever part is to be driven by the drive unit, as for instance the impeller 'of a refrigerant compressor, is mounted upon the lower projecting end 9' of the high speed output shaft, to which it may be secured by a nut (not shown) threaded onto the extreme end portion of the shaft. Preferably the bottom wall 26 of the drive unit enclosure is formedwith a hub portion 26' through which the output shaft projects, and the cylindrical outer wall of this hubportion is grooved, as at 66, to provide a labyrinth seal with a suitably configured hub portion on the part to be driven and thereby restrict the flow of fluids into the'interior of the drive unit enclosure; and also facilitate the maintenance, in a manner to be described, of a'high pressure zone at the mouth of the bore 25' through which the output shaft passes.

, The drive unit may be conveniently mounted by being gear teeth in the manner desecured to a wall of the machine it is to drive, such a Wall being indicated in broken lines and identified by the numeral 67 in Figure 1; and where the machine to be driven is a refrigeration apparatus, the mounting connection between the drive unit and the wall 67 should be fluid-tight. To this end, the connection is preferably made by bolting an upwardly facing flange 68 on the drive unit housing to the underside of the wall 67, with a sealing gasket 69 clamped therebetween.

Although the flange 68 could be on the upper section 13 of the drive unit housing, it is more conveniently formed as an integral part of its lower section 14. In any event, when the drive unit is thus mounted, all or most of its motor housing provided by the upper enclosure section 13 extends above the wall 67, while the remainder of the drive unit is below the wall 67, and, of course, within whatever chamber of which the Wall 67 forms a part. Accordingly, the only opening into or from the housing of the drive unit, namely, the clearance between the output shaft 9 and the wall of the bore 25' in the bottom wall 26 through which it projects, opens into the space below the wall 67, and hence into any chamber of which it forms a part. Therefore, the housing for the drive unit in effect becomes a part of the walls of such chamber.

Although the maintenance of a unidirectional flow of a gaseous medium into the drive unit at the point the output shaft emerges will no doubt prevent the loss of oil along the shaft, for added assurance against such loss a baflie 70 is provided directly beneath the lower output shaft bearing 40 to deflect and sling oil leaving the bearing 40 away from the shaft. Still further assurance against the loss of lubricant from the enclosure of the drive unit, is provided by maintaining a zone of high pressure at the mouth of the bore 25' through which the output shaft passes. For this purpose, a duct 71 is formed in the lower housing section 14. The inlet end of this duct is located at a convenient and readily accessible point on the exterior of the housing section '14, and its outlet opens to the space between the mouth of the bore 25' and the labyrinth seal formed by the grooves 66. Thus, upon connection of the inlet end of the duct 71 with a source of gas under pressure, a positive pressure is maintained at the mouth of the bore 25 which prevents the passage of oil out of the drive unit.

The maintenance of a high pressure zone at the mouth of the bore 25, will of course result in filling the interior of the drive unit enclosure with whatever gas is used. Hence, where the drive unit powers a refrigeration machine, the gas employed should be the gaseous refrigerant employed in the system.

Although the lubricating system of this invention affords good assurance against excessive agitation of the oil, the gears inevitably will produce a substantial amount of oil mist in the gear case, but the wall 36 which embraces the gears fairly well localizes this mist to the zone in which the gears and bearings are located, which of course is desirable.

The bafiiing effect of the wall 36 also has the advantage of dividing the interior of the lower enclosure section 14 into two compartments, one in which the mist is formed, and the other a relatively large quiet zone where the oil can more easily separate from the gaseous refrigerant. If desired, a heat exchanger 74 may be located in this quiet zone to maintain a temperature most conducive to the separation of the refrigerant gas from the oil. The top of the quiet zone thus would be another satisfactory location for the draw-01f duct 13'.

Though it is intended that the oil used in the drive unit be clean and free from abrasive particles of ferrous metal, to assure against carrying any such foreign matter into the bearings, an alnico magnet 75 is preferably mounted under the lower end of the motor shaft to entrap and remove such particles from the oil before it is pumped to the bearings.

From the foregoing description, taken in connection with the accompanying drawings, it will be readily apparent to those skilled in this art that this invention provides a gear-motor drive unit especially well adapted for use with refrigeration machines of the type which employ centrifugal impellers in their compressors, since it achieves the high speed necessary for driving suchimpellers and thereby adapts this form of compressor to use in relatively small-sized refrigeration machines. It will, of course, also be understood that although the invention is especially adapted to drive the impellers of compressors used in refrigeration machines, it may be used to advantage in any situation requiring a very high speed drive.

. What is claimed as our invention is:

1. An electric gear-motor drive unit comprising: a motor housing having a side wall portion and an end wall portion and being hermetically closed at its sides and at one end, the other end of the motor housing being open; a stator fixed in the motor housing; a rotor to coact with the stator; a motor shaft having the rotor fixed thereon and projecting from the open end of the motor housing; a bearing supporting structure having an imperforate side wall portion; means securing said side wall portion of the bearing supporting structure to the motor housing at the open end thereof so that the bearing supporting structure projects beyond the open end of the motor housing and the side wall portion of the bearing supporting structure forms substantially a continuation of the motor housing side wall portion; a pair of coaxial spaced apart motor shaft bearings, having the motor shaft journalled therein; means forming part of the bearing supporting structure mounting said bearings coaxially with the stator while leaving the motor housing open at its open end; said bearings constituting the sole support for the motor shaft; a drive gear fixed on the motor shaft be tween the bearings in which the shaft is journalled; an output shaft; a second pair of coaxial bearings carried by said bearing supporting structure and having the output shaft journalled therein; a driven gear fixed on the output shaft and meshing with the drive gear; and means on one of said side wall portions for mounting the entire unit on a supporting wall with a fluid tight connection at the juncture therebetween, and the interior of the motor housing in open communication with the space at one side of the Wall and the motor housing co-acting with said supporting wall to close on the space at said side of the wall from the space at the other side thereof.

2. An electric gear-motor drive unit comprising: a motor housing having a side wall portion and an end wal portion and being fully closed at its sides and at one end, the other end of the motor housing being open; a stator fixed in the motor housing; a rotor to coact with the stator; a motor shaft having the rotor fixed thereon and projecting from the open end of the motor housing; a unitary one piece bearing supporting structure having an imperforate side wall portion fixed to the motor housing at the open end thereof and projecting outwardly therefrom with the side wall portion of the bearing supporting structure forming substantially a continuation of the side wall portion of the motor housing, said bearing supporting structure being sufficiently open inside its side wall portion that the open end of the motor housing is not closed thereby; motor shaft bearing means mounted in said bearing supporting structure coaxially with the stator, having the motor shaft journalled therein; a drive gear fixed on the motor shaft; an output shaft; other bearing means carried by said supporting structure in which the output shaft is journalled and by which the output shaft is held in spaced parallel relation to the motor shaft; a driven gear fixed on the output shaft and meshing with the drive gear; a gear housing having opposite walls, one of which has an opening of a size to accommodate the bearing supporting structure and the other of which has a bore to accommodate the power take-off end portion of the output shaft, the remaining walls of the gear housing being imperforate; and a fluid tight connection between one of said side wall portions and the first designated Wall of the gear housing securing the gear housing to the connected motor housing and bearing supporting structure with the interior of the motor housing in open communication with the interior of the gear housing so that said housings together form a tightly closed enclosure into'which the only opening is the clearance between the output shaft and the bore in the gear housing wall through which it passes.

3. The electric gear-motor drive unit of claim 2 further characterized by the provision of duct means having an outlet adjacent to the mouth of the bore through which the output shaft passes and an inlet remote from said mouth, and through which fluid under pressure may be fed to the region adjacent to the mouth of said bore.

4. The electric gear-motor drive unit of claim 2 further characterized by the provision of flange means on one of saidhousings normal to the axis of the motor shaft for mounting the entire unit on a supporting wall with the motor housing and its contents at one side of said supporting wall and the gear housing and its contents at the other side thereof.

5. The electric gear-motor drive unit of claim 2 further characterized by the provision of flange means on one of said housings normal to the axis of the motor shaft for mounting the entire unit on a supporting wall with the motor housing and its contents at one side of said supporting wall and the gear housing and its contents at the other side thereof, said flange means being adapted to have a fluid tight connection with the supporting wall so that Where said supporting Wall is an outer wall of a hermetically sealed enclosure and the gear housing projects into said hermetically sealed enclosure to have its interior communicated with the interior of the hermetically sealed enclosure through the clearance between the output shaft and the edge of the hole in the gear housing wall through which it passes, the housing walls of the unit external to said hermetically sealed enclosure serve to maintain the hermetically sealed condition of the latter.

6. The electric gear-motor drive unit of claim 2 further characterized by the provision of means on one of said housings by which the entire unit may be mounted with its shafts vertical and the lower portion of the gear housing providing a sump to contain a supply of liquid lubricant, the sump thus provided being well below the gears so that the gears do not run in the lubricant in the sump; and pump means to elevate lubricant from a supply thereof in the bottom of the gear housing to all of said bearing means and the gears.

7. The electric gear-motor drive unit of claim 2 further characterized by the provision of flange means on one of said housings normal to the axis of the motor shaft to mount the entire unit on a horizontal supporting wall with its shafts vertical and the lower portion of the gear housing providing a sump to contain a supply of liquid lubricant, the sump thus provided being well below the gears so that the gears do not run in the lubricant in the sump; and means for delivering lubricant from a supply thereof in said sump to all of said bearing means and the gears, said means including a pocket formed in the upper end of the output shaft, a bearing cap disposed over the upper end of the output shaft, a relatively pointed downward protrusion on the bearing cap directed toward the pocket in the upper end of the output shaft, and means to convey liquid lubricant to the underside of the bearing cap so that upon shut-down lubricant covering the underside of the bearing cap flows down said projection and into said pocket.

7 8. A high speed gear-motor drive unit comprising: a hermetically sealed enclosure, the upper portion of which constitutes a motor housing and the lower portion a gear case and an oil sump, said upper and lower portions being in open communication with one another; a bearing support at the lower portion of the housing; a pair of vertically spaced coaxial upper and lower bearings in said bearing support; a motor shaft journalled in said bearings and extending up into the motor housing; a rotor on the upper portion of said shaft; a stator for the motor fixed in the upper portion of the enclosure and encircling the rotor to coact therewith; a drive gear fixed on the motor shaft between its bearings; a second pair of vertically spaced coaxial upper and lower bearings in said bearing support, the upper one of which is at an elevation between the upper motor shaft bearing and the drive gear; an output shaft journalled in said second pair of bearings with its upper end substantially at the level of its upper hearing so as to be below the level of the upper motor shaft bearing, and with its lower end portion protruding through the bottom wall of the enclosure for connection with a part to be driven; a pinion gear fixed on the output shaft and meshing with the drive gear on the motor shaft, said pinion gear being considerably smaller than the drive gear so that the output shaft travels at high speed; an upwardly opening pocket in the upper end of the output shaft; means defining an oil collecting trough in the bearing support directly beneath the upper motor shaft bearing to receive oil from the said bearing; an oil passage leading from said trough to the space above the upper output shaft bearing to conduct oil to said upper output shaft hearing when the unit is in operation; means to cause oil in said space upon shut down of the unit to accumulate in said pocket in the upper end of the output shaft; and means for forcing oil from the sump to the upper motor shaft bearing.

9. The structure set forth in claim 8, further characterized by the fact that the drive gear on the motor shaft is formed with an upwardly facing open topped trough, in which oil dropping from the upper motor shaft bearing accumulates upon shutdown; and further characterized by the provision of oil passage means extending through the rim of the drive gear from a point slightly above the bottom of said trough to the toothed surface of the gear, through which oil in the trough flows to the gear teeth upon starting of the unit.

10. The structure set forth in claim 8 wherein the means for forcing oil from the sump to the upper motor shaft bearing comprises an axial bore in the motor shaft from its lower end to a point above the elevation of its upper bearing; radial ports extending from said bore to the surface of the shaft at an elevation above the oil collecting trough so that oil thrown out through said ports splashes against the adjacent wall of the bearing support and onto the adjacent bearing; and means at the lower end of the motor shaft operable by rotation of the shaft to force oil from the sump upwardly into the bore.

11. The structure set forth in claim 10, further characterized by the provision of deflector means in the bearing support positioned to be impinged by oil which issues from said radial ports and to direct the same onto the adjacent bearing.

References Cited in the file of this patent UNITED STATES PATENTS 945,988 Simonds Jan. 11, 1910 2,126,385 Harbordt Aug. 8, 1938 2,639,394 Douglas May 19, 1953 2,697,179 Wendel Dec. 14, 1954 2,794,930 Rieser June 4, 1957 

